How Much Does It Cost To Run An Electric Heater?

It depends entirely on the wattage. At the current Ofgem Direct Debit price cap average of 26.11p/kWh, a 2000W (2kW) heater costs about 52p an hour, a 1500W heater about 39p an hour, and a 1000W heater about 26p an hour - the formula is simply (wattage ÷ 1000) × your price per kWh.

Run continuously for 4 hours (a common "heating an evening" reference point used by idealhome.co.uk), a 2kW heater costs roughly £2.09 at 26.11p/kWh. Run for a full 8 hours it would be roughly £4.18.

None of them are inherently cheaper per kWh - fan, convector/panel, oil-filled, halogen and infrared/quartz heaters all convert essentially 100% of the electricity they draw into heat. What actually changes your running cost is wattage (typically 1200W for halogen up to 2000-2500W for fan and convector types) and how long the thermostat keeps the element switched on, not the "type" itself.

Watt for watt, no - a 1500W oil-filled radiator and a 1500W fan heater cost the same to run per hour. Oil-filled radiators are often reported as cheaper in practice because their oil core retains heat and keeps radiating warmth for a while after the thermostat switches the element off, so the element itself is drawing power for less of the total time the room stays warm.

At 4 hours a day, 5 days a week and 26.11p/kWh, a 2000W heater comes to roughly £543 a year; a 1500W heater to roughly £407; and a 1200W heater to roughly £326. Heavier use (more hours or more days a week) scales this up directly - see the Scenario Analysis and Heater Type Comparison sections above for your own numbers.

As a rule of thumb, budget around 100 watts per square metre of floor space for an averagely insulated room, up to 125W/m² if the room is poorly insulated, or as little as 60-80W/m² in a well-insulated modern space. A 10m² average room would typically need around 1000W. Enter your room size and insulation level in the calculator to get your own recommended wattage.

Yes, if you're on a standard variable Direct Debit tariff. The cap sets the 26.11p/kWh default this calculator uses for 1 July-30 September 2026, reviewed roughly every three months by Ofgem. If you're on a fixed tariff, prepayment meter or Economy 7, replace the default with your own unit rate for an accurate result.

They're often cheaper in practice mainly because they're typically lower wattage - commonly 400W, 800W or 1200W on adjustable models, against 2000W+ for a typical fan or convector heater - not because the heating element itself is more efficient per watt. A 1200W halogen heater run for the same hours as a 2000W fan heater would cost about 40% less simply from using 40% less power.

It depends on how much of the home you're heating and for how long. A single portable electric heater warming one room for a few hours can be cheaper than running gas central heating for the whole house over the same period, but using electric heaters as your main heat source for a whole home over a full winter is typically far more expensive than gas central heating, because electricity costs roughly 3.5 times more per kWh than gas under the current Ofgem cap (26.11p vs 7.33p/kWh). This calculator covers the electric heater side only.

Yes, meaningfully. A heater with a thermostat switches the element off once the room reaches the set temperature and only switches back on once it drops again, so its real average power draw over an hour is lower than its rated wattage. This calculator assumes full-power operation for every hour you enter, so if your heater cycles on a thermostat, treat the "hours per day" figure as an estimate of on-time, not clock time, for a more accurate result.

Exactly 1 kWh, by definition - a 1000W (1kW) heater run for one hour uses 1 kilowatt-hour of electricity, costing about 26p at the current 26.11p/kWh Ofgem Direct Debit cap average.

No. Storage heaters charge overnight on a cheaper off-peak rate (commonly an Economy 7 tariff, with a lower night rate and a higher day rate than a standard single-rate tariff) and release that stored heat through the day. This calculator uses one flat price throughout, so it doesn't represent a storage heater's two-rate cost structure - check your Economy 7 night rate separately if that's what you have.

Rarely, once more than one or two rooms need heating for extended periods. Running several 2000W heaters across a house for hours at a time can easily add up to several times the cost of gas central heating for the same square footage, since electricity is roughly 3.5 times more expensive per kWh than gas under the current Ofgem cap. Electric heaters are usually most cost-effective as a supplement for one occupied room, not a whole-house replacement for central heating.

The most common reasons: your heater has a thermostat and isn't drawing full power for every hour it's switched on, your tariff's unit rate differs from the Ofgem cap default this calculator uses, your heater's true wattage differs from the typical figure a heater "type" defaults to (check the rating label on the heater itself), or your actual hours/days of use vary week to week. Update the calculator's price, wattage and usage fields with your own figures for a closer match.